Ball throwing machine



Dec. 7, 1954 GlLGOFF 2,696,204

BALL THROWING MACHINE Filed Oct. 20, 1951 3 Sheets-Sheet l l5 0 INVENTOR HERMQN GILGOFF ATTORNEY Dec. 7, 1954 H. GILGOFF BALL THROWING MACHINE 3 Sheets-Sheet 2 Filed 001:. 20. 1951 INVENTOR HERMQN GILGOFF Z, ATTORNEY Dec. 7, 1954 H. GILGOFF 2,696,204

BALL THROWING MACHINE Filed Oct. 20, 1951 3 Sheets-Sheet I5 22 lNVElJTOR HERMQN GILGOFF ATTORNEY United States Patent BALL THROWING MACHINE Herman Gilgoff, Brooklyn, N. Y.

Application October 20, 1951, Serial No. 252,244

12 Claims. (Cl. 124-7) This invention relates to a ball-throwing machine, and more particularly to an automatically operated ballthrowing machine for throwing baseballs, tennis balls or the like at predetermined intervals.

An object of the present invention is to provide a ball-throwing machine by means of which the balls may be thrown with considerable force at large distances.

Another object of the invention is to provide a ballthrowing machine which may be readily adjusted for throwing the balls at various distances.

A further object of the invention is to provide a ballthrowing machine which is reliable in operation.

Another object of the invention is to provide a ballthrowing machine with a feeding mechanism, which is automatically controlled by the ball-throwing arm for feeding one ball at a time from a magazine to the ballthrowing arm when the latter is in its ball-receiving position.

Still another object of the present invention is to provide a ball-throwing machine with an adjustable counter mechanism, by means of which the operation of the ball throwing machine may be readily adjusted for throwing a predetermined number of balls during a period of operations.

Other objects and structural details of the invention will be apparent from the following description when read in conjunction with the accompanying drawings forming part of this specification, wherein:

Fig. 1 is a side elevational view of a ball-throwing machine according to the invention,

Fig. 2 is a fragmentary side elevational view illustrating the counter device of the machine on an enlarged scale,

Fig. 3 is a fragmentary perspective view of a detail of the machine, some parts being broken away,

Fig. 4 is a fragmentary perspective view of another detail of the machine,

Fig. 5 is a perspective view of the ball-gripping device of the machine,

Fig. 6 is a fragmentary side elevational view of the machine showing the elements thereof in a different position,

Fig. 7 is a fragmentary view, partly in section, of the ball feeding device,

Fig. 8 illustrates the wiring diagram of the counter device, and

Fig. 9 is a side elevational view of a different embodiment of the gripping device of the machine.

Referring now to Figs. 1, 24, and 6, 20 generally indicates a support comprising a pair of longitudinal bars 22, carried by a pair of front legs 24 (only one leg being shown in the drawings) and a pair of rear legs 26 (only one leg being shown in the drawings). The front legs 24 are connected with each other by a cross-bar 28, and the rear legs are connected with each other by a crossbar 30. Furthermore, on each side of the support the front legs 24 and the rear legs 26 are connected with each other by a lower longitudinal bar 32 and an upper longitudinal bar 34, the latter being in the shape of an angleiron. Moreover, on each side of the support 20 a reinforcing element 36 is connected with the longitudinal bars 22, 32 and 34.

As best shown in Figs. 1 and 4, on each side of the support 20, an upright 38 is rigidly connected with the bars 22 and 34. Each upright has a platform 40 on which a bearing 42 is mounted. An actuating shaft 44 having a center crank 46 is rotatably mounted in said bearing 42. 8

A crank arm 48 is arranged on each end of said crank shaft 44. Each arm 48 carries a stud 50 connected with one end at an actuating spring 52, the other end of which is engaged with a loop 54 at one end of a cord 56 passing through an eyelet 58 attached to the lower longitudinal bar 32 of the support 20. A loop 60 at the other end of the cord 56 is engaged with an adjustable device, generally indicated by 62, mounted on the rear leg 26 of the gtipport 20 for adjusting the tension of the actuating spring The lower end of a ball throwing arm 64 is rigidly connected with the crank 46 of the crank shaft 44. As best shown in Figs. 1 and 5, a pair of gripping fingers 66 is swingably mounted at 68 at the upper end of the ball-throwing arm 64. Each finger 66 is provided with a serrated portion 70. Each of the gripping fingers 66 is provided with a slot 72 slidably engaged with a bolt 74 carried by the ball-throwing arm 64. The gripping fingers 66 connected by a cross-bar 75 may be held in a desired position relative to the ball-throwing arm 64 by means of a nut 76 screwed on the projecting end of the bolt 74.

As best shown in Figs. 1, 4, and 6, an engaging ele ment 78 is swingably suspended at 80 from lugs 82 carried by the crank portion 46 of the crank shaft 44. As shown in Figs. 3, 4 and 6, this engaging element 78 is provided at its lower end with a cam 84, the inclined surface of which merges into the surface of an edge of a lower engaging plate 86 arranged on said engaging element 78. Furthermore, at a distance from said cam 84 and at an opposite side of the engaging element 78 a second engaging cam 88 is arranged, the inclined surface of which merges into the surface of an edge of a second engaging plate 90. Springs-92 (see Figs. 4 and 9) are stretched between pins 94 projecting from the engaging element 78 and pins 96 projecting from the uprights 38. The springs 92 are weaker than the actuating springs 52.

As best shown in Figs. 1, 3 and 9, a rod 98 is carried by bearings 100 slidably mounted in slots 102 (only one slot being shown) of bars 104 rigidly secured to and depending from the longitudinal rails 34. Each bar 104 carries at its lower end a lug 106 provided with a threaded bore 108. The upper ends of set screws 110 engaged with said threaded bores 108 are in engagement with the slidable bearings 100 for setting same in a predetermined position. The shaft 98 carried by said bearings 100 is arranged for cooperative engagement with the cam 84.

As best shown in Figs. 1, 3 and 6, a locking device, generally indicated by 112, is mounted on a plate 114 carried by the longitudinal rails 34. This locking device 112 comprises a substantially cylindrical casing 116 slidably receiving a locking pin 118 projecting therefrom at one end thereof. The projecting end of this locking pin 118 has an inclined surface arranged for cooperative engagemept with the cam 88 of the engaging element 78. A longitudinal rod 120 rigidly connected with the locking pin 118 passes through a bore of the casing 116 at the opposite end thereof and carries a stub 122. The locking pin 118 is under the action of a spring 124 wound around the rod 120 inside the casing 116, said spring 124 urging the locking pin 118 into an extreme position towards the engaging element 78, said extreme position being limited by an engagement of the stub 122 with the end wall of the casing 116. A transverse rod 126 connected with the locking pin 118 passes through slots 128 (only one being shown) arranged on each side of the casing 116. This transverse rod 126 is arranged for engagement with sliders 130 slidably engaged with housings 132 carried by the longitudinal bars 34.

As shown in Fig. 1, an electro-motor 134 mounted on a plate 136 carried by the bars 32 drives through a belt drive 138 the input shaft 140 of a speed reducing transmission 142 mounted on a bracket structure 144 carried by the support 20. A sprocket wheel 146 secured to the output shaft 148 of the speed reducing transmission 142 drives through a chain 150 (see Figs. 1, 3 and 9) a sprocket wheel 152 keyed to a driving crank shaft, generally indicated by 154, journalled in suitable bearings of the longitudinal bars 34. This crank shaft 154 has a center crank 156 provided with a roller 158 capable of engagement with the engaging element 78 and the platform 86 thereof during a rotation of the crank shaft 154.

Furthermore, this crank shaft 154 is provided with,

two arms 160 arranged at an obtuse angle to the arms of the center crank shaft 156. Each of the arms 160. carries a roller 162 capable of engagement with the end of the slider 130 during a rotation of the crank shaft 154.

Moreover, as best shown in Figs. 1 and 2, an actuating element 164 of a counter device, generally indicated by 166, is secured to one end of the crank shaft 154. This actuating element 164. has a projection 168 which, during a rotation of the crank shaft 154, may engage one or the other collar 170 of a set of collars mounted on a. sleeve 172 slidably arranged on a rod 174- secured to one of the bars 34.. The sleeve 172' is under the action of a spring 176 stretched between its right hand end (as, viewed in Fig, 2) and a stationary portion of the support 26 for urging the sleeve 172 in. the direction of the arrow A.

Opposite the actuating element 164 av double armed locking element 178 is swin-gably mounted at 180 on a .plate 132 secured to theupper bar 22 of the. support 20.

The lower arm 184 of said locking element 173 arranged for engagement with one. or the. other of the collars 170 of the slidable spring loaded sleeve 172; is pivoted at 186 to one end of a connecting rod 188,, the: other end of which is pivoted at 190 to the projecting end 192 of the core of a solenoid 194. This solenoid is mounted on a, plate 196 secured to the support 29. One end of a spring 198 is connected with the pivotal connection: 186 between the connecting rod- 188- and the lower end 184 of the locking element 178; the other end of this spring 198 is connected with a bolt 209 secured to the support 20. This spring tends to rotate the double armed locking lever 178 in counter-clockwise direction. The movement of the locking element 178 in counter-clockwise direction is limited by a stop 202 arranged on the plate 182 for engagement with the upper arm 264 of the. locking element 178. A. member 206 having a bore for slidable engagement with the rod 174. and carrying the movable resilient terminal 208 and the stationary terminal 210 of an electric switch, generally indicated by- 212, is adjustably arranged on said rod 174. Themember 206 may be held in an adjusted position by a set screw 214 which may be brought into engagement with one or the other recess of a series of recesses, 216v arranged on the rod 174..

As shown in Fig. 2 the resilient terminal, 268* of the switch 212 is normally in contact with the stationary terminal 210 for closing the motor circuit 218. (see Fig. 8). During the operation of the machine the crank shaft 154' is rotated and, during each revolution of said crank shaft, the projection 168 of the. actuating element 164 comes into engagement with a collar 170 of the. sleeve 1 72, whereby the latter is-displaced one step on the rod 174 against the action of the; spring 176. Upon disengagement of the projection 168 from a collar 170, the sleeve 172 is held in itsv position by the end 1S4v of the locking element 178. Depending on the adjustment of the member 206, an end plate 220- of the sleeve 172 comes into engagement with, the movable resilientterminal 203 of the switch 212. after a. predetermined number of revolutions of the crank shaft 154. Asshown. in Fig, 8, the engagement of the end plate 220'with the movable resilient terminal 208 causes adisengagement of the latter from the stationary terminal 210, whereby the motor circuit 218 is interrupted for. a stopping'of the motor 134.

As shownin Fig. 8, a coin. receiving, device 222 of any suitable construction is arranged in the solenoid circuit 224. When upon insertion of a coin the spring loaded slider 226 of the, coin. receiving device 222 connects the terminals 228 and 230 of the latter with each other, the solenoid circuit 224 is. closed whereby the solenoid 194 is excited and the connecting rod 188 is thrown in, the direction of the arrow B causing a rocking of, the locking element, 1 78vv about its pivot. 186 against the action of. the spring 198in clockwise direction. This rocking movement of. the locking element 178, in turn, results in: the disengagement of itsend 184; from a: collar 170 of the sleeve 1,72,,so that the latter isimmediately returned to itsstarting position. limited by an abutment of: its right hand end plate 232 (see. Fig. 2) against a stop pin 234 projecting from the rod 174. Thisreturn movement of the sleeve: 172 causes an immediate closing' of. the switch. 212 of the movable resilient terminal 208; now disengaged from; the. leftehand end plate-2200f thersl'eeve, whereby the motor. circuit. 218 isv closed. for astart; of} the: motor: 1343 Upon release of the spring loaded slider 226 of the coin receiving device 222 the solenoid circuit. 224. 18.111. terrupted at the terminals 228 and 230, so that now the spring 198 may return the rockable locking element 178 into the position shown in Fig. 2, wherein it is ready for holding the sleeve 172 in its respective position obtained by a stepwise displacement by the actuating member 164-.

Referring now to Figs. 1 and 7, a supporting device, generally indicated by 236, carrying a magazine 233 is attached to the support 20 by screws or the like. A double-armed lever 246 sw-inga-bly mounted on the supporting device 236. at 242 is normally held by means of a spring 244 in the position shown in full lines in Figs. 1 and 7. The spring 244 is stretched between the arm 246 of the lever 246 and the element 247 of the supporting device 236. A first holding pin 24S pivoted to the arm 25!) of the double-armed lever 240 at 252 passes through a bore 254 of the magazine 238 and a second holding pin 256 pivoted to the arm 246 of the lever 240 at 258 passes through a bore 260 of the magazine. When the lever 24%. is in the position shown in full lines in Fig. 7, the first holding pin 248 projects into the magazine for holding engagement with the first ball of a supply of calls 262 placed in the magazine 238. Thus, all of the balls are prevented from leaving the magazine. One leg. of a U-shaped member 264', preferably made of resilient material, is secured to the arm 256 of the double-armed lever 240 by screws 266. A spring 268 is arranged between the legs of said U-shaped member 264. When, in a manner to be described hereinafter, the ball throwing arm 64 (Fig. 1) is moved from its substantially upright position shown in full lines in said Fig. 1, into its ball receiving position 64' shown in dash and dotlines in Fig. 1, the cross-bar of the gripping head 66 comes into engagement with the resiliently supported upper leg of the U-shaped member 264, whereby the latter together with the arm 250 is swung downwardly, so that the double-armed lever reaches the position 240 shown in dash and dot lines in Fig. 7'. This movement of the lever 240 causes a retraction of the first holding pin 248 from the interior of the mag.- azine 238 for release of the first ball. At the same time the second holding pin 256 enters the interior of the magazine, whereby it comes into holding engagement with the ball of the supply of balls which now is the first ball. The released ball enters the gripping head and is now held by the latter.

When, in a manner to be described hereinafter, the ball throwing arm is released from its ball receiving position 64' and returns into its upright position 64 under the action of the actuating spring 52 for throwingv the ball, the gripping head 66 is disengaged from the U- shaped member 264 so that now the double-armed lever carrying the U-shaped member 264 returns from its position 240 (Fig. 7) into its original positionv 24il'under the action of the spring 244. This position is limited by an. engagement between the upper leg ofthe U-shaped member 264 and the end of the magazine. During this return movement of the lever 249, the. second holding pin 256 is retracted from the interior of the magazine 238 and the first holding pin 248 enters the interior of the magazine so that the supply of balls may roll downwardly in the inclined magazine until the now first ball comes into engagement with the first holding pin 248.

The operation of the machine is as follows:

Let us assume that, after the last operation of the machine, the actuating crank shaft 64, the ballthrowing arm 64, the engaging element 78 and the driving shaft 154 with its crank 156 are in the position shown in full lines in Figs. 1 and 4, respectively, and that the sleeve 172 of the counter device 166 is in the position shown in Fig. 8 for holding the switch 212 in. open position.

In order to start the machine, a coin is insertedinto thev coin receiving device 222 whereby in the manner described above the solenoid 194- is energized for releasing the spring loaded sleeve 172 of the counter device 166 so as to cause a closing of the switch 212 for closing the motor circuit 218.

During a revolution of the driving crank shaft 154. in the direction of the arrow C (see Figs. 1. and 3), the roller 158 of the crank 156 contacts the engaging element 781 and rolls somewhat along the surface thereof until it comes mto engagement with. the platform 86 of the engaging element 78, as shown'in dash and dot lines in Fig. 6. During the continuation of the rotation of the driving shaft 154 in the direction of the arrow C, the crank 156, with its roller "1 engaged with the platform 86, pulls the engaging element 78 downwardly whereby the ball throwing arm 64 is swung in counter-clockwise direction and the actuating springs 52 connected with the arms 48 of the driving shaft 44 are tensioned.

During the downward movement of the engaging element 78, the cam 84 thereof is brought into engagement with the shaft 98, as shown in Fig. 3. By the action of this cam 84, the downward movement of the engaging element 78 is controlled in such a way that, during a continuation of the rotation of the tensioning arm 156 of the driving shaft 154, the roller 158 becomes disengaged from the platform 86.

However, before this disengagement takes place, the upper cam 88 of the engaging element 78 engages the inclined surface of the locking pin 118, displacing same against the action of the spring 124.

Upon disengagement of the cam 88 from the locking pin 118 during the downward movement of the engaging element 78, the locking pin 118 is automatically pushed outwardly by the action of the spring 124, so that it comes into locking engagement with the upper surface of the platform 90, as shown in full lines in Fig. 6. At this time, the lower cam 84 of the engaging element 78 is still in engagement with the rod 98, so that the engaging element 78 is prevented from a swinging movement in counter-clockwise direction, and, consequently, the upper platform 90 cannot be disengaged from the locking pin 118. Thus, the ball throwing arm 64 is held in its ball receiving position against the action of the actuating springs 52.

During above described downward movement of the engaging element 78 and movement of the ball throwing arm 64 into its ball receiving position, the springs 92 stretched between the engaging element 78 and the uprights 38 are tensioned. Furthermore, when the ball throwing arm 64 reaches its ball receiving position 64', as shown in dash and dot lines in Fig. 1, a ball is automatically fed to the gripping head 66 from the magazine 238 in the manner described above. The ball then rests in the gripping head 66.

During the continuation of the rotation of the driving shaft 154 in the direction of the arrow C after above described locking engagement between the locking pin 118 and the platform 90 of the engaging element 78, the roller 158 of the crank 156 becomes disengaged from the platform 86, as shown in full lines in Fig. 6.

Thereafter, the rollers 162 of the releasing arms 160 (see Fig. 3) come into engagement with the ends 270 of the sliders 130 during the continuation of the rotation of the driving shaft 154. Said releasing arms 160 cause a displacement of the sliders 130 by the rollers 162 in longitudinal direction, whereby the ends 272 of said sliders coming into engagement with the transverse rod 126 cause a displacement of the locking pin 118 against the action of the spring 124. This displacement of the locking pin 118, in turn, causes a release of the locking engagement between the pin and the platform 90, so that now the actuating springs 52 cause a sudden and fast rotation of the ball throwing arm 64 in clockwise direction for throwing the ball engaged with the gripping head 66. The engaging element 78 now acts as a pendulum the movements of which are dampened by the springs 92. Thus, by the action of the engaging element 78, and the actuating spring 52 having a tendency to hold the arms 48 of the driving shaft 44 and the ball throwing arm 64 in the position shown in Figs. 1 and 4, the ball throwing arm 64 reaches soon after the throwing of a ball the position shown in Figs. 1 and 4, and the machine is ready for throwing another ball in the manner described above.

During each revolution of the driving shaft 154 the ball throwing arm 64 receives and throws one ball. Furthermore, during each revolution of the actuating shaft 154, the sleeve 172 of the counter device 166 is advanced one step by the projection 168 of the actuating element 164 secured to the actuating shaft 154.

As will be readily understood, the ball throwing machine throws as many balls as the sleeve 172 of the counter device 166 is advanced until the switch 212 is opened by the end plate 220 of the sleeve 172 as shown in Fig. 8. Thereafter, the machine is automatically stopped and is ready for operation upon insertion of another coin into the coin receiving devlce.

If it is desired to set the operation of the machine in such a way that a lower or higher number of balls may be thrown before the counter device 166 automatically shuts off the motor 134, the member 206 (Fig. 2) carrying the switch 212 is displaced on the rod 174 for en gagement of its set screw 214 with another recess 216 which is nearer to or farther away from the end plate 220 of the sleeve 172 when the latter is in its extreme position, wherein its plate 232 abuts against the stop 234. This position of the sleeve 172 may be obtained during the standstill of the machine by disengaging the locking element 184 from a collar of the sleeve 172 by hand.

An adjustment of the trajectory of the ball thrown by the machine may be readily obtained by an adjustment of the position of the gripping head 66 relative to the ball throwing arm 64 by means of the adjusting means 72, 74 and 76.

While according to Fig. 5 the gripping fingers 66 are provided with serrated surfaces 70, according to the embodiment shown in Fig. 9, the gripping fingers 66 adjustably mounted on the ball throwing arm 64 are provided with a series of spring loaded pins 274 having conical heads. The spring loaded pins 274 are shiftably arranged and, of course, their extreme outward position is limited by stops (not shown). The spring loaded pins 274 may be depressed by a ball during the throwing thereof, whereby they may compensate for uneveness in a ball, thus improving the throwing operation.

If desired, the sleeve 172 with the collars 170 of the counter device may be replaced by any other mechanism acting in the manner of a rack capable of cooperation with the locking element 178 and the nose 168.

I have described preferred embodiments of this invention, but it is understood that this disclosure is for the purpose of illustration, and that various omissions or changes in shape, proportion and arrangements of parts, as well as the substitution of equivalent elements for those herein shown and described, may be made without departing from the spirit and scope of the invention, as set forth in the appended claims,

What I claim is:

l. A ball throwing machine comprising in combination: a support, a ball throwing arm swingably mounted on said support, an actuating spring connected with said ball throwing arm and said support, an engaging element swingably suspended from said ball throwing arm, a first engaging surface on said engaging element, a second engaging surface on said engaging element, tensioning means movably arranged on said support, said tensioning means being capable of temporary engagement with said first engaging surface for bringing said ball throwing arm into a ball receiving position and tensioning said actuating spring, spring loaded locking means movably arranged on said support for locking engagement with said second engaging surface when the ball throwing arm is in its ball receiving position, releasing means capable of disengaging said locking means from said second engaging surface for releasing said ball throwing arm and causing a ball throwing movement of the latter under the action of said actuating spring, and a drive operatively connected with said tensioning means and said releasing means for bringing said ball throwing arm into said ball receiving position by means of said tensioning means and, thereafter, releasing said ball throwing arm by means of said releasing means.

2. A ball throwing machine comprising in combination: a support, a ball throwing arm swingably mounted on said support, an actuating spring connected with said ball throwing arm and said support, an engaging element swingably suspended from said ball throwing arm, a first engaging surface on said engaging element, a second engaging surface on said engaging element, a shaft rotatably mounted on said support, a drive connected with said shaft for rotating same, a tensioning element mounted on said shaft, said tensioning element being capable of temporary engagement with said first engaging surface during a revolution of said shaft for bringing said ball throwing arm into a ball receiving position and tensioning said actuating spring, spring-loaded locking means movably arranged on said support for locking engagement with said second engaging surface when the ball throwing arm is in its ball receiving position, and a releasing element mounted on said shaft, said releasing element being capable of temporary engagement with said locking means during a revolution of said shaft so as to disengage same from said 7 second engaging. surface for releasing said ball throwing arm and causing a ball-rthrowingmovement of. the latter under the action of said actuating spring;

3. In a ball throwing machine as claimed in claim 2, a cam on said engaging element, and abutting means on said support, said cambeing arranged for engagement with said abutting means during the movement of said engaging element by said tensioning element so as to secure a disengagement of said tensioning element from said. first engaging surface at-- a predetermined interval.

4. In a ball throwing machine as claimed in claim 2, acam on said engaging element, abutting means adjustably mounted on said support, and setting means associated with said abutting means for setting. same in a predetermined position, said cam being arranged for engagement with said abutting means during the movement of said engaging element by said tensioning element so as to secure a disengagement of said tensioning element from said first engaging surface at a predetermined interval.

5.- A ball throwing machine comprising in combination: a support, a ball throwing arm swingably mounted on said support, an actuating spring connected with said ball throwing armand said support, an engaging ele ment swingably suspended from said ball throwing arm, a first platform arranged on and projecting from said engaging element, a second platform arranged on and projecting from said engagingelement, a shaft rotatably mounted on said support, a drive connected with said shaft for rotating same, a tensioning element mounted on said shaft, said tensioning element being capable of temporary engagement with said first platform during a.- revolution of said shaft for bringing said ball throwing arminto a ball receiving position and tensioning said actuating spring, spring loaded locking means shiftably arranged on said support for locking engagement with said second platform when the ball throwing arm is in its ball receiving position,- and a releasing. element mounted on saidshaft, said releasing element being capable of temporary engagement with said locking means during a revolution of said shaft so as to disengage same from said second platform for releasing said ball throwing arm and causing a ball throwing movement of the latter under the action of said actuating spring.

6. Ina ball throwing machine as claimed in claim 5, acam arranged on said engaging element for displacing said spring loaded. locking means against the action of its spring during the movement of the engaging element by saidtensioning element so as to bring said locking means into position for engagement with said second platform under the action of its spring.

7. In a ballthrowing machine as claimed in claim 5, said first and second platforms being arranged at opposite sides of said engaging element.

8. A ball throwing machine comprising in combination: a support, a ball throwing arm swingably mounted on said support, an actuating spring connected with said ball. throwing arm and said support, an engaging element swingably suspended from said ball throwing arm, a first platform arranged on and projecting from one side of said engaging element, a first cam arranged on said engaging element on the same side as said first platform, abutting means on said support for cooperation with said first earn, a second platform arranged on and projecting from the opposite side of said engaging, element, a second cam arranged on said engaging element on the same side as said second platform, a shaft rotatably mounted on said support, a drive connected with said shaft for rotating same, a tensioning element mounted on said shaft, said tensioning elementbeing capable of temporary engagement with said first platform during a revolution of said shaft for bringing said ball-throwing arm into a ball receiving position and tensioning said actuating spring, spring loaded locking means shiftably arranged on said support for locking engagement with said second platform when the ball throwing arm is in its ball receiving position, and a releasing element mounted on said shaft, said releasing element being capable of temporary engagement with said locking means during a revolution of said shaft so as to disengage same from said second platform for releasing said ball throwing arm and causing a ball throwing movement of the latter under the action of said actuating spring, said first cam being arranged for engagement-with said abutting means during the movement of said engaging element by said tensioning element so as to secure a disengagement of said tensioning elementfrom said first engaging surface at a predetermined interval, and said second cam being arranged for displacing said spring loaded locking means against the action of its spring during the movement of the engaging element by said tensioning element so as to bring said locking means into position for engagement with said second platform under the action of its spring.

9. In a ball throwing machine as claimed in claim 8, resilient means arranged between said engaging element and said support for dampening the movements of said engaging element upon release of said structure.

10. A ball throwing machine comprising in combination: a support, a ball throwing arm swingably mounted on said support, an actuating spring connected with said ball throwing arm and said support, an engaging element swingably suspended from said ball throwing arm, an engaging surface on said engaging element, a shaft rotat'ably mounted on said support, a tensioning element mounted on said shaft, said tension'mg element being capable of temporary engagement with said engaging surface during a revolution of the shaft for bringing said ball throwing arm into a ball receiving position and tensioning said actuating spring, locking means arranged on said support for locking engagement with the structure including said ball throwing arm and said engaging element when the ball throwing arm is in its ball receiving position, releasing means operatively connected with said rotatable shaft and arranged for disengaging said loclring means from said structure at a predetremined interval during a revolution of said shaft so as to release said structure and cause a ball throwin movement of the ball throwing arm under the action or said actuating spring, and electrornotor connected with said shaft for rotating same, a motor switch, a motor circuit including said electromotor and said motor switch, said motor switch including resilient means tending to hold same in closed position, a toothed member movabiy mounted on said support, and an actuating element secured to said shaft, said actuating element being arranged for displacing said toothed member one step during each revolution of said shaft, and said toothed member being capable of engaging said motor switch for opening same against the action of itsresilient means upon displacement after a predetermined number of steps.

'11. In a ball throwing machine as claimed in claim 10, said motor switch being adjustable relative to said toothed member.

12. A ball throwing machine comprising in combination: a support, a ball throwing arm swingably mounted on said support, an actuating spring connected with said ball throwing arm and said support, an engaging element swingabl'y suspended from said ball throwing arm. an engaging surface on said engaging element, a shaft rotatably mounted on said support, a tensioning element mounted on said shaft, said tensioning element being capable of temporary engagement with said engaging surface during a revolution of the shaft for bringing said ball throwing arm into a ball receiving position tensioning said actuating spring, locking means arranged onsaid support for locking engagement with the structure including said ball throwing arm and said engaging element. when the ball throwing arm is in its ball receiving position, releasing means operativelyconnected with said rotatable shaft and arranged for disengaging said locking means from said structure at a predetermined interval during a revolution of said shaft so as to release said structure and cause a ball throwing movement of the ball throwing arm under the action of said actuating spring, an electromotor connected with said shaft for rotating same, a motor switch, a motor circuit inciuding said electromotor and said motor switch, said motor switch including resilient means tending to hold same in closed position, a toothed member movably mounted on said support for displacement from an inactive position into active position, a spring arranged between said support and said too hed member for urging same into its inactive position, an actuating element secured to said shaft, said actuating element being arranged for advancing said toothed member one step during each revolution of said shaft, amovable locking pawl arranged for engagement with said toothed member so as to hold same in an advanced position, said motor switch being adjustable in selected positions relative to 10 the inactive positionbof said toothed member, said toothed References Cited in the file of this patent mem er eing capa e o engaging said motor switch for opening same against the action of its resilient means UNITED STATES PATENTS upon displacement from its inactive position into an ac- Number Name Date tive position after a predetermined number of steps de- 5 1,194,093 Stroup Aug. 8, 1916 pending on the selected position of the motor switch, a 1,204,645 Boardman Nov. 14, 1916 coin-controlled closing switch, and electromagnetic 1,707,726 Jeter Apr. 2, 1929 means in circuit with said coin-controlled closing switch 1,733,394 Bible et a1. Oct. 29, 1929 and associated with said pawl for disengaging same from 1,831,545 Puff Nov. 10, 1931 said toothed member upon energization by a closing of 10 1,897,955 Hoke Feb. 14, 1933 said coin-controlled closing switch so as to release said 2,267,525 Kemp Dec. 23, 1941 toothed member for return into its inactive position by 2,469,016 Stopper May 3, 1949 said spring. 2,650,585 Farre Sept. 1, 1953 

